US3425903A - Nuclear power plant protective system employing logic materices - Google Patents

Nuclear power plant protective system employing logic materices Download PDF

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Publication number
US3425903A
US3425903A US667908A US3425903DA US3425903A US 3425903 A US3425903 A US 3425903A US 667908 A US667908 A US 667908A US 3425903D A US3425903D A US 3425903DA US 3425903 A US3425903 A US 3425903A
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contacts
matrices
sensing devices
reactor
relay
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US667908A
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Frank Bevilacqua
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Combustion Engineering Inc
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Combustion Engineering Inc
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C7/00—Control of nuclear reaction
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C7/00—Control of nuclear reaction
    • G21C7/36—Control circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • NUCLEAR POWER PLANT PROTECTIVE SYSTEM EMPLOYING LOGIC MATRICES Filed Sept. l5, 1967 Sheet of 5 MN M @www mm mm RM .w%% ⁇
  • NUCLEAR POWER PLANT PROTECTIVE SYSTEM EMPLOYING LOGIC MATRIcEs Filed Sept. l5, 1967 Sheet 5 of 5 PDM/E SUPPLY CLUTCHES a [/V l/E/VTO FRA/VK BEVILACQUA By C A TT/QNE 3,425,903 NUCLEAR POWER PLANT PRTECTIVE SYSTEM EMPLOYING LOGIC MATRICES Frank Bevilacqua, Windsor, Conn., assignor to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Sept. 15, 1967, Ser. No. 667,908 U.S. Cl. 176--20 10 Claims Int. Cl.
  • a nuclear reactor safety control system wherein a plurality of independent sensing devices are employed to monitor each of a number of reactor operating variables operative to terminate operation of the reactor whenever at least a plurality of the sensing devices associated with any one variable simultaneously respond to a preset condition of the monitored variable.
  • the present invention is therefore directed to a nuclear reactor safety control system that avoids the above-mentioned disadvantages by providing a relatively simple arrangement of matrix circuits permitting high reliability of the actuation of the reactor protective function and at the same time being capable of preventing needless reactor shutdown in case of occasional component malfunction or of spurious sensor actuation.
  • a control circuit contains a plurality of parallelly-arranged matrices, each comprised of a number of series-connected branches, which, in turn, contain a number of parallelly-connected contacts operated by the respective sensing devices employed to monitor each of a number of separate plant variables.
  • Relay means operative to terminate operation of the reactor by actuating a control rod scram controller are connected in seires with each matrix and are operable in response to the actuation of an appropriate number of contacts as determined by their arrangement in the respective matrices.
  • the control circuit is arranged such that the number of branches in each matrix corresponds to the number of separate plant variables being monitored; the number of parallelly-connected contacts in each branch corresponds to the number of sensing devices whose response to a deviation from safe operating conditions is required in order that the operation of the reactor be terminated; and the number of matrices employed in the control circuit corresponds to the number necessary to produce all required logic combinations of sensing devices monitoring the same variable.
  • FIGURE l is a schematic diagram of a nuclear reactor safety control system according to the present invention employing a two-out-of-three actuation logic
  • FIGURE 2 is a schematic diagram of a system similar to that of FIGURE 1 but employing a two-out-of-four actuation logic;
  • FIGURE 3 is a schematic diagram of a system similar to those of FIGURES 1 and 2 but employing a three-outof-four actuation logic;
  • FIGURES 4 and 4a are schematic diagrams of a modiiied nuclear reactor safety control system similar to that of FIGURE 2.
  • the safety control system is operative to monitor each of the many operating variables of a nuclear reactor utility plant and to suspend operation of the reactor whenever any one of the variables exhibits a condition that is determined to be dangerous to plant operation.
  • Some of the variables that may be monitored by appropriate sensing devices in a typical plant are as follows: primary coolant ow; pressure in the pressurizer; water level in the steam generator; Ipresence of load; condition of neutron flux; etc.
  • the present system employs redundant instrumentation in that a plurality of sensing devices indicated as in the drawings are arranged to independently monitor each of the respective variables.
  • the sensing devices 10 each have a plurality of contacts 12 associated therewith which are actuated by a relay coil 14.
  • each contact 12 can be arranged to be operated by a single independent relay.
  • the contacts 12 are normally open contacts and the relay coils 14 are generally energized during reactor operation to close the contacts such that the system operates in accordance with a fail-safe principle.
  • each sensing device 10 is arranged to de-energize its associated relay coil 14 upon the monitored variable exhibiting a preset condition, which condition is determined to be undesirable for safe reactor operation.
  • the sensing devices 10 are grouped in a plurality of channels which, while being the preferred arrangement for reasons hereinafter explained, facilitates identification of the respective components.
  • Each sensing device 10 is identified by the variable that it monitors with each of the respective variables being indicated by a single-digit numeral 1, 2, 3 n.
  • those sensing devices monitoring low primary coolant ow are designated 1, high pressure in the pressurizer 2, and low pressure in the pressurizer 3.
  • Apparatus for monitoring only three variables are illustrated in the diagram for the sake of brevity. It is to be understood, however, that any number of variables can be monitored as indicated by the sensing devices identified as n.
  • the respective channels into which the sensing devices are grouped are indicated by appropriate upper-case letters A, B, C, D, etc.
  • any number of channels can be employed depending upon the number of sensed devices selected to monitor each variable.
  • the individual sets of contacts 12 associated with each sensing device ⁇ 10 and operatively connected with each relay 14 are indicated by lower-case letters a, b, c, etc., the number of contacts employed being determined by the number of matrices that comprise the control circuit of the system.
  • each of the components of the system can be identified according to the channel and variable with which it is associated.
  • contacts Ala shown in the disclosed control circuits are the first set of contacts a associated with the sensing device monitoring low coolant flow r1 in the rst channel A.
  • the nuclear reactor safety control system is provided with a control circuit operative to actuate mechanism, indicated generally as the control rod scram controller 22, that is effective to drop the control rods of the reactor into their fully-extended position within the reactor core, thereby terminating operation of the reactor.
  • a control circuit operative to actuate mechanism, indicated generally as the control rod scram controller 22, that is effective to drop the control rods of the reactor into their fully-extended position within the reactor core, thereby terminating operation of the reactor.
  • the control circuit 20 is an arrangement of the contacts 12 actuated by the respective sensing devices 10 so arranged that the control rod scram controller 22 will be actuated only when a predetermined number of sensing devices monitoring each variable respond to a preset indication of a deviation from safe reactor operation.
  • sensing devices 10 monitoring the same variable In order to actuate the control rod scram controller 22, sensing devices 10 monitoring the same variable must be simultaneously actuated to thereby prevent needless shutdown of the reactor as was possible in systems of the prior art when the malfunction or spurious actuation of sensing devices monitoring separate variables were effective to terminate reactor operation.
  • FIGURE l there is illustrated a diagrammatic representation of a control system employing three sensing devices 10 to monitor each of a number of variables 1, 2, 3 n and effective to terminate operation of the reactor whenever any two of the three sensing devices monitoring any one variable are actuated.
  • the sensing devices 10 are shown as being grouped in channels A, B, and C, with each channel containing a plurality of sensing devices with each monitoring one of the separate variables.
  • Two contacts 12 are associated with each sensing device to be operated thereby and are respectively identified as contacts a and b.
  • the contacts 12 which are normally open contacts are actuated to a closed position by the energization of relay coils 14 whenever the reactor is placed in operation.
  • the contacts 12 can be actuated to an open position by de-energization of their respective relay coils as will occur when the sensing device operating each responds to a preset condition in the variable being monitored.
  • the control system includes a control circuit 20 cornprising a number of similar series-parallel connections of contacts 12 operated by the various sensing devices 10 and arranged in matrices 24 that are shown as being connected in parallel across power leads 26 and 28.
  • Each matrix 24 contains a number of series-connected branches, indicated as 30, 32, 34, and 36, each consisting of parallelly-connected pairs of contacts operated by sensing devices monitoring the same variable.
  • each matrix 24 is identified by a combination of upper-case letters that correspond to the channels with which the contacts of each branch are associated.
  • matrix AB contains branches 30 through 36 consisting of contactss Ala and Bla, A2a and B2a, A3a and B3n and and Ana and Bna operated by the sensing devices grouped in channels A and B.
  • matrix AC contains branches 30 through 36 consisting of contacts Alb and Cla, A2b and C2a, A3b and C3a, and Anb and Cna operated by sensing devices grouped in channels A and C.
  • matrix BC which contains contacts operated by sensing devices grouped in channels B and C.
  • each matrix 24 Connected in series with each matrix 24 is a relay coil 38 adapted to operate an associated set of contacts 40.
  • the respective relay coils 38 and contacts 40 are identified in the drawings by subscripts that correspond to the appropriate matrix with which each is associated.
  • the contacts 40 are series-connected in a line 42 containing the control rod scram controller 22 such that actuation of any one of the contacts 40 is effective to actuate the controller.
  • the operation of the control system of FIGURE 1 is as follows.
  • the relay coils 14 associated with all of the sensing devices 10 are energized to thereby close the associated contacts 14 that are arranged in the matrices 24 comprising the control circuit 20.
  • the relay coils 40 connected in series with each of the matrices 24 are therefore energized to close their associated contact 42.
  • all of the sensing devices A1, B1, and C1 will be actuated to de-energize their relay coils 14, thereby opening the contacts a and b associated with each.
  • FIGURE 2 there is shown a safety control system embodying the present invention wherein four sensing devices 10 are employed to monitor each variable 1, 2, 3 n and the arrangement of the control circuit is such that actuation of any two of the four sensing devices will actuate the control rod scram controller 22.
  • the modied system differs from that of FIGURE l in that the added sensing devices 10 are grouped in channel D. Since the system employs a two-out-of logic similar to that of FIGURE l each matrix 24 comprises branches 30 through 36 made up of two parallelly-connected sets of contacts. Due, however, to the presence of an additional channel D, and the two-out-of-four logic requirement the number of matrices 24 in the control circuit 20 must be increased from three as in the previous arrangement to six.
  • matrices AB, AC, AD, BC, BD, and CD are identilied as matrices AB, AC, AD, BC, BD, and CD.
  • the number of matrices in this arrangement requires that each sensing device 10 be provided with an additional set of contacts such that, in this arrangement, each relay 14 operates three contacts, a, b, and c.
  • the line 42 that contains the control rod scram controller 22 now includes six series- COIlneCted Contacts 40 ⁇ AB, 40Ac, 40AD, 40130, 40BD, and 40GB operated by the relay coils 38 connected in series with each of the respective matrices 24.
  • control system of this embodiment is substantially identical with that of FIGURE 1, the only difference being that additional current paths dened by the presence of additional matrices are provided to control the actuation of the controller 22. If any two or more of the four sensing devices 10 employed to monitor any one variable are actuated, the current path defined by two or more of the matrices 24 will be disrupted to de-energize the associated relay(s) 38 thereby opening the associated contacts 40 in line 42 to actuate the controller. As long as only one sensing device 10 is actuated, all of the circuit paths defined by the matrix 24 will remain unbroken to prevent actuation of the controller 22 thus permitting operation of the reactor to continue.
  • the control system illustrated in FIGURE 3 is one incorporating the inventive concept wherein the actuation of three, instead of two, of the four sensing devices 10 of the FIGURE 2 arrangement are required to actuate the control rod scram controller 22.
  • the channels A, B, C, and D are arranged in an identical fashion to those of the FIGURE 2 arrangement with each channel containing one sensing device 10 for monitoring each of the plant operating variables 1, 2, 3 n and each sensing device operating three contacts a, b, and c.
  • the matrices 24 comprise seriesconnected branches 30 through 36 that each consist of three parallelly-connected contacts.
  • each matrix 24 terminates in a series-connected relay coil 38 having an associated set of contacts 40.
  • the contacts 40 are series-connected in a line 42 containing the control rod scram controller 22 whereby actuation of any one of the matrix-operated relay coils 38 will eifect actuation of the controller.
  • FIG- URES 4 and 4a The modied form of the invention illustrated in FIG- URES 4 and 4a is a system substantially the same as that of FIGURE 2 but wherein the control circuit, here indicated as 20', is arranged for operation off a plurality of independent energy sources.
  • the control circuit here indicated as 20'
  • reliability of the safety system is increased in that the lprotective function is not rendered inoperative by failure of one or more energy sources.
  • each channel A, B, C, and D can be physically isolated from one another as can be each sensing device 10 of which the channels are comprised.
  • each matrix conduit 24 can be arranged in separate isolated compartments or the like.
  • each of the matrices 24 is connected to two independent energy sources 44, which sources can be those that supply power to each of the respective channels A, B, C, and D.
  • the matrix indicated as matrix AB is connected in parallel between independent power sources 44A and 44B.
  • matrix AC is connected in parallel between independent power sources indicated as 44A and 44C.
  • the remaining matrices AD, BC, BD, and CD are similarly connected in parallel between independent power sources. Because electrical energy is supplied to the control circuit in this manner a power failure in one of the sources will not afect the operability of the associated matrices.
  • relay coils 38 connected in series with each of the matrices of FIGURE 2 are replaced by relay groups indicated as 46 and the subscript appropriate to the matrix to which each is connected.
  • Each relay group comprises four parallelly-connected coils each operating an associated set of contacts indicated as 1, 2, 3, and 4 in each group. These sets of contacts are arranged in the circuitry of FIGURE 4a which corresponds to line 42 of FIGURE 2 such that there are now four independent lines operable to actuate the control rod scram controller.
  • the scram controller and its operating circuitry of FIGURE 4a replaces line 42 in the FIGURE 2 embodiment of the invention and comprises a plurality of control rod closure coils 48 connected in parallel between two independent sources of D.C. power 50 and 52.
  • Each of the D C. power sources 50 and 52 receives electrical energy from two independent A.C. sources which can be the same power sources supplying the respective channels 44A and 44B in the case of D.C. source 50 ⁇ and 44C and 44D in the case of D.C. source 52.
  • Connection is made between the A.C. and D.C. power sources by means of lines 54 and 56 through manually actuated double poledouble throw switches SS.
  • the switches 58 enable D.C. sources 44A or 44B and D.C.
  • circuit breaking contacts 60 are contained in each of the .lines 54 and 56. These are operated by relay coils 62, 64,
  • lines 70, 72, 74, and '76 which are connected to A.C. sources 44A, 44B, 44C, and 44D, respectively.
  • Series-connected in each of the lines 70, 72, 74, and 76 are one set of contacts 1, 2, 3, or 4, operated by each of the coils in each relay group 46 associated with the control circuit matrices. These contacts are identied by their appropriate number together with an appropriate prefix to indicate the matrix with which each set of contacts is associated.
  • the operation of the scram controller of FIGURE 4a is such that whenever an affected matrix is actuated to de-energize its connected relay group 46 all of the coils in the affected group will be de-energized thereby opening the contacts operated by each.
  • relay group 46M when relay group 46M; is actuated to de-energize each of the coils in that group contacts ABI in line 70, ABZ in line 72, ABS in line 74, and AB4 in line 76 will be opened to break the line in which each is contained.
  • Breaking lines 70, 72, 74, or 76 causes relays 62, 64, 66 or 68 to be de-energized thus opening contacts 60 that supply A.C. power to the D.C.
  • safety control systems constructed according to the present invention are characterized by flexibility of design in that any number of plant operating variables can be accommodated simply by providing an increasing number of branches in each of the matrices of the control circuit.
  • Such systems can further provide for alterations in the actuation logic by providing for the actuation of any number of sensing devices to be required for initiating the protective function. This is accomplished simply by increasing the number of parallelly-connected contacts that comprise each of the matrix branches.
  • a control system operative to produce a desired effect upon the occurrence of a predetermined plurality of sensors monitoring any single variable responding to a preset condition in the associated variable, said control system including:
  • switch means operated by each of said sensors and operative to actuate a plurality of contacts upon response to a preset condition by the associated sensor
  • branches each consisting of a number of parallelly-connected contacts operated by separate sensors monitoring the same variable, the number of contacts contained in each of said branches corresponding to the number of sensors whose response is required to produce the desired effect
  • said relay means comprises:
  • a control system according to claim 1 wherein said contacts are actuable to an open position in response to the actuation of the respective switch means.
  • said relay means comprises:
  • said sensors are arranged in groups each containing one sensor monitoring each variable;
  • a nuclear reactor safety control system wherein a plurality of sensors are employed to monitor each of a plurality of independent plant operating variables, said control system being operative to terminate operation of the reactor upon the occurrence of a predetermined plurality of sensors monitoring any single variable responding to a preset condition in the associated variable, said control system including:
  • switch means associated with each of said sensors and operative to actuate a plurality of closed contacts to an open position upon responding to a preset condition
  • said branches each consisting of a number of parallelly-connected contacts operated by said switsh means associated with separate sensors monitoring the same variable, the number of contacts contained in each of said branches corresponding to the number of sensors whose response to a preset condition is required to terminate operation of the reactor;
  • said relay means comprises:
  • a control system according to claim 7 wherein said relay means comprises:
  • said sensors are arranged in mutually isolated channels each containing one of the sensors monitoring each of said variables;
  • a control system according to claim 6 wherein said matrices are operably connected to independent energy sources.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)
  • Testing And Monitoring For Control Systems (AREA)
US667908A 1967-09-15 1967-09-15 Nuclear power plant protective system employing logic materices Expired - Lifetime US3425903A (en)

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JP (1) JPS5111279B1 (bg)
CH (1) CH499163A (bg)
ES (1) ES358132A1 (bg)
FR (1) FR1588260A (bg)
GB (1) GB1197528A (bg)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3985613A (en) * 1973-07-31 1976-10-12 Combustion Engineering, Inc. Reactor trip on turbine trip inhibit control system for nuclear power generating system
US4054486A (en) * 1974-12-11 1977-10-18 Commissariat A L'energie Atomique Nuclear reactor fail-safe unit having the function of control relay and current regulation
US4105496A (en) * 1974-12-11 1978-08-08 Commissariat A L'energie Atomique Method and device for electronic control with positive safety
US4427620A (en) 1981-02-04 1984-01-24 Westinghouse Electric Corp. Nuclear reactor power supply
US4447851A (en) * 1980-07-07 1984-05-08 Imperial Chemical Industries Limited Trip system
US4697093A (en) * 1985-01-23 1987-09-29 Westinghouse Electric Corp. Testable, fault-tolerant power interface circuit for controlling plant process equipment
US4696785A (en) * 1985-10-31 1987-09-29 Westinghouse Electric Corp. Testable voted logic power circuit and method of testing the same

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4208890A (en) 1977-09-26 1980-06-24 Servis Domestic Appliances Limited Control circuits in or for washing, drying and the like machines or other apparatus
JPH0379280U (bg) * 1989-12-04 1991-08-13

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2973458A (en) * 1956-11-09 1961-02-28 British Thomson Houston Co Ltd Safety systems for nuclear reactors
AT219171B (de) * 1960-09-12 1962-01-10 Landis & Gyr Ag Einrichtung zur Überwachung des Neutronenflusses in einem Atomreaktor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2973458A (en) * 1956-11-09 1961-02-28 British Thomson Houston Co Ltd Safety systems for nuclear reactors
AT219171B (de) * 1960-09-12 1962-01-10 Landis & Gyr Ag Einrichtung zur Überwachung des Neutronenflusses in einem Atomreaktor

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3985613A (en) * 1973-07-31 1976-10-12 Combustion Engineering, Inc. Reactor trip on turbine trip inhibit control system for nuclear power generating system
US4054486A (en) * 1974-12-11 1977-10-18 Commissariat A L'energie Atomique Nuclear reactor fail-safe unit having the function of control relay and current regulation
US4105496A (en) * 1974-12-11 1978-08-08 Commissariat A L'energie Atomique Method and device for electronic control with positive safety
US4447851A (en) * 1980-07-07 1984-05-08 Imperial Chemical Industries Limited Trip system
US4427620A (en) 1981-02-04 1984-01-24 Westinghouse Electric Corp. Nuclear reactor power supply
US4697093A (en) * 1985-01-23 1987-09-29 Westinghouse Electric Corp. Testable, fault-tolerant power interface circuit for controlling plant process equipment
US4696785A (en) * 1985-10-31 1987-09-29 Westinghouse Electric Corp. Testable voted logic power circuit and method of testing the same

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Publication number Publication date
DE1764955A1 (de) 1972-01-13
FR1588260A (bg) 1970-04-10
DE1764955B2 (de) 1972-07-20
JPS5111279B1 (bg) 1976-04-09
ES358132A1 (es) 1971-02-16
GB1197528A (en) 1970-07-08
CH499163A (fr) 1970-11-15

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